Posts Tagged ‘gravity theory’

You Can’t Get Entangled Without A Wormhole

December 6, 2013 Leave a comment

Quantum entanglement is one of the more bizarre theories to come out of the study of quantum mechanics — so strange, in fact, that Albert Einstein famously referred to it as “spooky action at a distance.”

Essentially, entanglement involves two particles, each occupying multiple states at once — a condition referred to as superposition. For example, both particles may simultaneously spin clockwise and counterclockwise. But neither has a definite state until one is measured, causing the other particle to instantly assume a corresponding state. The resulting correlations between the particles are preserved, even if they reside on opposite ends of the universe.

But what enables particles to communicate instantaneously — and seemingly faster than the speed of light — over such vast distances? Earlier this year, physicists proposed an answer in the form of “wormholes,” or gravitational tunnels. The group showed that by creating two entangled black holes, then pulling them apart, they formed a wormhole — essentially a “shortcut” through the universe — connecting the distant black holes.

Now an MIT physicist has found that, looked at through the lens of string theory, the creation of two entangled quarks — the building blocks of matter — simultaneously gives rise to a wormhole connecting the pair.

The theoretical results bolster the relatively new and exciting idea that the laws of gravity holding together the universe may not be fundamental, but arise from something else: quantum entanglement.

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Is Antimatter Anti-Gravity?

Antimatter is strange stuff. It has the opposite electrical charge to matter and, when it meets its matter counterpart, the two annihilate in a flash of light. Four University of California, Berkeley, physicists are now asking whether matter and antimatter are affected differently by gravity as well. Could antimatter fall upward – that is, exhibit anti-gravity – or fall downward at a different rate?

Almost everyone, including the physicists, thinks that antimatter will likely fall at the same rate as normal matter, but no one has ever dropped antimatter to see if this is true, said Joel Fajans, UC Berkeley professor of physics.

And while there are many indirect indications that matter and antimatter weigh the same, they all rely on assumptions that might not be correct. A few theorists have argued that some cosmological conundrums, such as why there is more matter than antimatter in the universe, could be explained if antimatter did fall upward.

In a new paper published online on April 30 in Nature Communications, the UC Berkeley physicists and their colleagues with the ALPHA experiment at CERN, the European Organization for Nuclear Research in Geneva, Switzerland, report the first direct measurement of gravity’s effect on antimatter, specifically antihydrogen in free fall. Though far from definitive – the uncertainty is about 100 times the expected measurement – the UC Berkeley experiment points the way toward a definitive answer to the fundamental question of whether matter falls up or down.

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Einstein’s Gravity Theory Passes Toughest Test Yet

Artist’s impression. Credit: ESO/L. Calçada

Artist’s impression. Credit: ESO/L. Calçada

A strange stellar pair nearly 7,000 light-years from Earth has provided physicists with a unique cosmic laboratory for studying the nature of gravity. The extremely strong gravity of a massive neutron star in orbit with a companion white dwarf star puts competing theories of gravity to a test more stringent than any available before.

Once again, Albert Einstein’s General Theory of Relativity, published in 1915, comes out on top.

At some point, however, scientists expect Einstein’s model to be invalid under extreme conditions. General Relativity, for example, is incompatible with quantum theory. Physicists hope to find an alternate description of gravity that would eliminate that incompatibility.

A newly-discovered pulsar — a spinning neutron star with twice the mass of the Sun — and its white-dwarf companion, orbiting each other once every two and a half hours, has put gravitational theories to the most extreme test yet. Observations of the system, dubbed PSR J0348+0432, produced results consistent with the predictions of General Relativity.

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